A transient splicing fission matrix calculation method and device for a core model

Abstract

The present invention provides a method and device for calculating a transient splicing fission matrix of a core model, the method comprising: obtaining a pre-established fission matrix database; wherein the fission matrix database comprises fission matrices corresponding to a uniform model of the core model under various material properties; selecting corresponding target fission matrix elements from the fission matrix database based on the current state of the target material properties of the core model, splicing a transient splicing fission matrix corresponding to the current state of the target material properties based on the target fission matrix elements; and correcting the transient splicing fission matrix based on the distribution boundary information of the target material properties in the current state to obtain a corrected transient splicing fission matrix. The present invention can simulate the transient process of the enrichment, control rods and temperature of the core model under a changing state, so that the calculated transient splicing fission matrix is ​​more in line with the actual situation, and improves the calculation accuracy and calculation rate of the transient splicing fission matrix.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear reactors, and in particular to a method and device for calculating a transient splicing fission matrix of a core model. Background Art

[0002] The splicing fission matrix is ​​a method proposed to solve the eigenvalue problem. The splicing fission matrix method requires pre-calculating a set of databases with different material properties, and using the splicing method to generate a real fission matrix from the database according to the specific location of the material. The transient fission matrix method is a hybrid method based on the fission matrix for transient analysis. The transient fission matrix usually uses the Monte Carlo method to pre-calculate a set of response functions related to time, space and reaction neutron type, and based on these response functions, the transient process of the entire core is determined. It can combine the advantages of deterministic methods and Monte Carlo methods for accurate transport calculations. However, the current transient fission matrix needs to calculate the response relationship of each spatial point to each spatial point. The overhead in database calculation is too large and it is difficult to apply to three-dimensional core problems. When calculating complex transient situations, such as control rod drop / injection, it is necessary to calculate the database under various conditions, and it is impossible to solve the transient problem of continuous changes. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a method and device for calculating the transient splicing fission matrix of a core model, which can simulate the transient process of the enrichment, control rods and temperature of the core model under any changing state, and can make the calculated transient splicing fission matrix more in line with the actual situation, thereby improving the calculation accuracy and calculation rate of the transient splicing fission matrix.

[0004] In order to achieve the above purpose, the technical solution adopted by the embodiment of the present invention is as follows:

[0005] In a first aspect, an embodiment of the present invention provides a method for calculating a transient splicing fission matrix of a core model, comprising:

[0006] Acquire a pre-established fission matrix database; wherein the fission matrix database includes fission matrices corresponding to a uniform model of the core model under multiple material properties, and the multiple material properties include any one or more of enrichment, control rods, and temperature;

[0007] Based on the current state of the target material property of the core model, corresponding target fission matrix elements are selected from the fission matrix database, and based on the target fission matrix elements, a transient spliced ​​fission matrix corresponding to the current state of the target material property is obtained by splicing;

[0008] The transient splicing and fission matrix is ​​corrected based on the distribution boundary information of the target material properties in the current state to obtain a corrected transient splicing and fission matrix.

[0009] Further, an embodiment of the present invention provides a first possible implementation manner of the first aspect, wherein the fission matrix database includes a fission matrix of the core model under the material properties of the control rods fully inserted and the control rods fully withdrawn;

[0010] The step of selecting corresponding target fission matrix elements from the fission matrix database based on the current state of the target material property of the core model, and obtaining a transient spliced ​​fission matrix corresponding to the current state of the target material property based on the splicing of the target fission matrix elements comprises:

[0011] During the movement of the control rods of the core model, obtaining the boundary position between where the control rods are inserted and where the control rods are not inserted;

[0012] Based on the intersection position, a target fission matrix element corresponding to the area where the control rods are inserted is obtained from the fission matrix with all control rods inserted, and a target fission matrix element corresponding to the area where the control rods are not inserted is obtained from the fission matrix with all control rods removed;

[0013] The target fission matrix elements corresponding to the area where the control rod is inserted are spliced ​​with the target fission matrix elements corresponding to the area where the control rod is not inserted, so as to obtain the transient spliced ​​fission matrix corresponding to the movement of the control rod.

[0014] Further, an embodiment of the present invention provides a second possible implementation manner of the first aspect, wherein the fission matrix database includes the fission matrix of the core model at different values ​​of the enrichment;

[0015] The step of selecting corresponding target fission matrix elements from the fission matrix database based on the current state of the target material property of the core model, and obtaining a transient spliced ​​fission matrix corresponding to the current state of the target material property based on the splicing of the target fission matrix elements comprises:

[0016] Obtaining the boundary lines between different enrichment distribution areas on the fuel rods of the core model;

[0017] Based on the dividing line, the target fission matrix elements in the corresponding area are obtained from the fission matrix database of each enrichment level that is equal to the current enrichment levels of the fuel rod, and the target fission matrix elements in each enrichment distribution area are spliced ​​to obtain the transient spliced ​​fission matrix corresponding to the enrichment change process of the fuel rod.

[0018] Further, the embodiment of the present invention provides a third possible implementation manner of the first aspect, wherein the fission matrix database includes the fission matrix of the core model at different temperatures;

[0019] The step of selecting corresponding target fission matrix elements from the fission matrix database based on the current state of the target material property of the core model, and obtaining a transient spliced ​​fission matrix corresponding to the current state of the target material property based on the splicing of the target fission matrix elements comprises:

[0020] Obtaining a boundary line between different temperature distribution areas of the core model;

[0021] Based on the dividing line, the target fission matrix elements in the corresponding area are obtained from the fission matrix database of each temperature corresponding to the current temperature of each area of ​​the core model, and the target fission matrix elements in each temperature distribution area are spliced ​​to obtain the transient spliced ​​fission matrix corresponding to the temperature distribution change process in the core model.

[0022] Further, an embodiment of the present invention provides a fourth possible implementation of the first aspect, wherein the step of correcting the transient splicing fission matrix based on the distribution boundary information of the target material property in the current state to obtain a corrected transient splicing fission matrix includes:

[0023] Calculating the boundary correction ratio corresponding to each area based on the distribution boundary information of the target material property in the current state;

[0024] Based on the boundary correction ratio corresponding to each area, the matrix elements at the corresponding positions in the transient splicing and fission matrix are corrected to obtain a corrected transient splicing and fission matrix.

[0025] Further, an embodiment of the present invention provides a fifth possible implementation of the first aspect, wherein the regions include a first region and a second region, and the target material property has different states in the first region and the second region; the step of calculating the boundary correction ratio corresponding to each region based on the distribution boundary information of the target material property in the current state includes:

[0026] Calculating the fission rate corresponding to the real model of the target material property in the current state, recorded as the first fission rate;

[0027] Calculate the fission rate corresponding to the infinite uniform model under the target material property value in the first region, which is recorded as the second fission rate;

[0028] Calculate the fission rate corresponding to the infinite uniform model under the target material property value in the second region, which is recorded as the third fission rate;

[0029] Calculating a ratio of the second fission rate to the first fission rate to obtain a boundary correction ratio corresponding to the first region;

[0030] The ratio of the third fission rate to the first fission rate is calculated to obtain a boundary correction ratio corresponding to the second area.

[0031] Furthermore, the embodiment of the present invention provides a sixth possible implementation of the first aspect, wherein the step of establishing the fission matrix database includes:

[0032] Replacing the target material properties of all regions in the core model with the same material properties to simulate a uniform model of the core model, performing fixed source calculation on the uniform model, and obtaining a fission matrix of the target material properties;

[0033] Fixed source calculation is performed on the uniform model of the core model under various material properties to obtain the fission matrix database.

[0034] In a second aspect, an embodiment of the present invention further provides a transient splicing fission matrix calculation device for a core model, comprising:

[0035] an acquisition module, configured to acquire a pre-established fission matrix database; wherein the fission matrix database includes fission matrices corresponding to a uniform model of the core model under a plurality of material properties, wherein the plurality of material properties include any one or more of enrichment, control rods and temperature;

[0036] A splicing module, used for selecting corresponding target fission matrix elements from the fission matrix database based on the current state of the target material property of the core model, and splicing the target fission matrix elements to obtain a transient splicing fission matrix corresponding to the current state of the target material property;

[0037] A correction module is used to correct the transient splicing and fission matrix based on the distribution boundary information of the target material properties in the current state to obtain a corrected transient splicing and fission matrix.

[0038] In a third aspect, an embodiment of the present invention provides an electronic device, comprising: a processor and a storage device; the storage device stores a computer program, and when the computer program is executed by the processor, it executes the method as described in any one of the first aspects.

[0039] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described in any one of the above-mentioned first aspects are executed.

[0040] An embodiment of the present invention provides a method and device for calculating a transient splicing fission matrix of a core model, the method comprising: obtaining a pre-established fission matrix database; wherein the fission matrix database comprises fission matrices corresponding to a uniform model of the core model under a variety of material properties, the variety of material properties comprising any one or more of enrichment, control rods and temperature; based on the current state of the target material properties of the core model, selecting corresponding target fission matrix elements from the fission matrix database, splicing the target fission matrix elements to obtain a transient splicing fission matrix corresponding to the current state of the target material properties; and correcting the transient splicing fission matrix based on the distribution boundary information of the target material properties in the current state to obtain a corrected transient splicing fission matrix. The present invention can simulate the transient process of the enrichment, control rods and temperature of the core model under changing states by splicing the transient splicing fission matrix of the target material properties in the current state based on a pre-established fission matrix database, thereby avoiding the problem that the transient fission matrix method needs to repeatedly calculate the database in the continuous change process. The calculation method is simple, and by correcting the transient splicing fission matrix based on the distribution boundary information of the target material properties in the current state, the calculated transient splicing fission matrix can be made more in line with the actual situation, thereby improving the calculation accuracy and calculation rate of the transient splicing fission matrix.

[0041] Other features and advantages of the embodiments of the present invention will be described in the following description, or some features and advantages can be inferred or determined without doubt from the description, or can be learned by implementing the above-mentioned techniques of the embodiments of the present invention.

[0042] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 A flow chart of a method for calculating a transient splicing fission matrix of a core model provided by an embodiment of the present invention is shown;

[0045] Figure 2 A schematic diagram of splicing a transient splicing fission matrix during control rod movement provided by an embodiment of the present invention is shown;

[0046] Figure 3A transient splicing fission matrix calculation flow chart provided by an embodiment of the present invention is shown;

[0047] Figure 4 A schematic structural diagram of a transient splicing fission matrix calculation device for a core model provided by an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be described below in conjunction with the drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0049] At present, the splicing fission matrix theory is a method first proposed to solve the eigenvalue problem. The splicing fission matrix method requires pre-calculating a set of databases with different material properties, and using the splicing method to generate a real fission matrix from the database according to the specific location of the material. For the eigenvalue problem of a reactor system, the fission matrix fission source F at the spatial grid i is i The following formula:

[0050]

[0051] Among them, a i,j is the number of neutrons produced by fission of the source neutrons in grid j in space unit i, F j is the fission matrix fission source at spatial grid j; k is the multiplication factor.

[0052] There are two ways to calculate the fission matrix. One is to use the fixed source calculation mode of the Monte Carlo program. It is necessary to perform fixed source calculations in each grid of all spatial grids. The result of each calculation is a column of the fission matrix. In order to achieve appropriate accuracy, the spatial grid must be small enough, so as the system becomes larger, the amount of calculation of this method gradually increases. The other is dynamic calculation, which is a standard effective multiplication factor k eff The calculation method is to calculate the fission matrix in a loop by marking the neutrons in the grid.

[0053] The neutron transport equation for fixed source calculation is:

[0054]

[0055] Among them, dψ m (s) is the neutron flux in direction m and at the local coordinate s, Σ t (s) is the total macroscopic cross section, Q(s) is the total source (including fission source and scattering source). The steps of Monte Carlo simulation of fixed source calculation include:

[0056] Construct a geometric model and initialize the random number generator; determine the source particle state information through source distribution sampling; obtain the movement of each step of the particle through transport length sampling; when reaching a certain position, determine the reaction process of the particle through collision nuclide and reaction type sampling; determine whether the particle history has ended and whether secondary particles have been generated through the state after the reaction; after simulating the source particle, simulate its secondary particles in turn; after cyclically simulating the source particle, calculate the corresponding physical quantities, such as the fission rate, based on the statistical results.

[0057] The transient fission matrix method is a hybrid method based on the fission matrix for transient analysis. The transient fission matrix usually uses the Monte Carlo method to pre-calculate a set of response functions related to time, space and reaction neutron type, and solves the transient process of the entire core deterministically based on these response functions. In many cases, the advantages of deterministic methods and Monte Carlo methods can be combined to perform accurate transport calculations.

[0058] Compared with the fission matrix, the transient fission matrix not only needs to be counted on a time scale, but also needs to be classified according to the types of neutrons generated and emitted. xy (i,j,k) represents the number of neutrons of type y generated by the x-type source neutrons in grid j during the time (k-1)*Δt to k*Δt, which triggers the fission in grid i. x and y are used to distinguish the types of neutrons generated and emitted in grids i and j, i.e., prompt neutrons and delayed neutrons. xy (i,j,k) are calculated using a Monte Carlo code with fixed source time.

[0059] Known transient fission matrix Time integration mode can be defined for:

[0060]

[0061] The matrix corresponds to the fission matrix Σa i,j The difference between algorithms is that Contains the types of neutrons generated and produced.

[0062] According to the transient fission matrix, the neutron dynamics equation can be obtained:

[0063]

[0064] Among them, S p (k) is the source distribution of prompt neutrons at time k; λ d represents the decay constant of the delayed neutron precursor nucleus; represents the transient fission matrix, x represents the incident neutron type, y represents the type of neutron produced by the reaction, x and y include delayed neutrons d and prompt neutrons p; C d Represents the distribution of delayed neutron precursor nuclei.

[0065] The splicing fission matrix theory was first proposed as a method to solve the eigenvalue problem. The splicing fission matrix method requires a set of databases with different material properties to be calculated in advance, and the database is spliced ​​to generate a real fission matrix according to the specific location of the material. The splicing fission matrix theory also proposes a correction ratio method to compensate for the discontinuity at the material boundary. Due to its advantages in calculation speed and calculation accuracy, the splicing fission matrix theory has become increasingly popular in recent years and has been applied to core criticality calculations and spent fuel pool simulations.

[0066] In order to achieve appropriate calculation accuracy, when using the fission matrix method to simulate real problems, a very fine grid is often divided, which makes the fission matrix of the system very large. If the core layout changes, the real fission matrix needs to be recalculated every time. In steady-state calculations, the spliced ​​fission matrix method is proposed to approximate the variable real fission matrix.

[0067] The splicing fission matrix method is based on a simple assumption. From the above formula (1), it can be seen that the elements of the fission matrix are equal to the number of neutrons that are emitted by a neutron starting from the jth region and undergoing fission in the i-th region. Fission is mainly caused by thermal neutrons, which cannot propagate too far, so the properties of the terminal region largely determine the fission situation there. Therefore, it can be assumed that the elements of the fission matrix are only related to the properties of the terminal region, that is, the i-th region.

[0068] When the properties of the end points are the same, the data with the same relative position relationship can be used as a replacement. For example, when the entire area is infinitely uniform, the properties of the end points at each position are the same, and a i,j To replace a i',j' In this case, only one fixed source calculation is needed to obtain the fission matrix elements a in all regions j to n,j Then the complete fission matrix can be obtained by splicing. When the properties of the end point regions are different, it is necessary to calculate a for different end point situations. i,j , generating multiple sets of databases. According to the specific end point position, use the corresponding a i,j Splicing generates the final fission matrix.

[0069] The transient fission matrix usually uses the Monte Carlo method to pre-calculate a set of response functions related to time, space and reaction neutron types, and deterministically solves the transient process of the entire core based on these response functions. In many cases, it can combine the advantages of deterministic methods and Monte Carlo methods to perform accurate transport calculations. However, the transient fission matrix method still has some problems: 1. The overhead in database calculation is too large, and it is necessary to calculate the response relationship of each spatial point to each spatial point, which is difficult to apply to three-dimensional core problems; when calculating complex transient situations, such as control rod drop / injection, it is necessary to calculate the database under various conditions, and the transient fission matrix cannot solve the transient problem of continuous change. The spliced ​​fission matrix method is currently only used in steady-state calculations. 2. The data of the spliced ​​fission matrix method does not distinguish between the types of emitted neutrons and produced neutrons, namely delayed neutrons and prompt neutrons; for the time scale, the spliced ​​fission matrix method only counts the total neutrons generated without time discreteness.

[0070] In order to improve the above problems, an embodiment of the present invention provides a method and device for calculating the transient splicing fission matrix of a core model. The embodiment of the present invention is introduced in detail below.

[0071] This embodiment provides a method for calculating the transient splicing fission matrix of a core model, which can be applied to electronic devices such as computers. Figure 1 The flow chart of the transient splicing fission matrix calculation method of the core model shown in the figure mainly includes the following steps:

[0072] Step S102, obtaining a pre-established fission matrix database;

[0073] The above-mentioned fission matrix database includes the fission matrix corresponding to the uniform model of the core model under various material properties, and the various material properties include any one or more of enrichment, control rods and temperature; enrichment includes the U235 enrichment type in all nuclear fuel rod fuels; control rod conditions include the full rod insertion state and the full rod withdrawal state; temperature includes the highest temperature and the lowest temperature during system operation.

[0074] The fission matrix database includes fission matrices under material properties of fully inserted and fully withdrawn control rods, fission matrices of the core model under different values ​​of the enrichment, and fission matrices of the core model at different temperatures. The fission matrices under the above material properties can be obtained by simulating a uniform model using a fixed source calculation method.

[0075] Step S104, based on the current state of the target material property of the core model, corresponding target fission matrix elements are selected from the fission matrix database, and a transient spliced ​​fission matrix corresponding to the current state of the target material property is obtained based on the splicing of the target fission matrix elements;

[0076] According to the geometric arrangement of the real model of the core model and the material properties of the specific positions, the corresponding matrix elements in the database are spliced ​​to generate the transient splicing fission matrix of the real model.

[0077] g x,y (i,j,t) is an element in the fission matrix. The x-type source neutron in grid j triggers fission in grid i and produces the number of y-type neutrons produced within the time (k-1)*Δt to k*Δt. Among them, x and y are used to distinguish the types of neutrons produced and emitted in grids i and j, namely prompt neutrons and delayed neutrons.

[0078] When the properties of the neutron endpoint regions in the reactor are the same, data with the same positional relationship can be used as a substitute. For example, when the entire region is infinitely uniform, the endpoint properties at each position are the same, and g can be used. x,y (i,j,t) to replace g x,y (i', j', t), where i' and j' are grids with the same position relationship as i and j. In this case, only one fixed source calculation is needed to obtain the fission matrix elements g from j to all regions. x,y (n,j,t). Then the complete splicing fission matrix can be obtained by splicing. When the properties of the end regions are different, it is necessary to calculate g for different end cases. x,y (i,j,t), generate multiple sets of databases. According to the specific end point position, use the corresponding g x,y (i,j,t) are concatenated to generate the final fission matrix.

[0079] For example, for the control rod movement problem, first, a database containing two states is generated: the fission matrix of the inserted control rod and the fission matrix of the fully lifted control rod. Based on the actual position of the control rod at the end position, that is, whether there is a control rod at a certain height, the matrix elements in the database are selected and spliced ​​to generate the transient spliced ​​fission matrix of the real model.

[0080] Step S106, based on the distribution boundary information of the target material properties in the current state, the transient splicing and fission matrix is ​​corrected to obtain a corrected transient splicing and fission matrix.

[0081] All elements in the transient splicing fission matrix database are arranged according to material properties (such as enrichment, control rod conditions, temperature, etc.) and obtained by simulating the uniform model using a fixed source calculation method. The data of various material properties are prepared into a set of databases. Although the transient splicing fission matrix is ​​generated by splicing fixed source calculations, there are still differences in source distribution between the real model and the infinite uniform distribution model. The above method ignores the influence of neutrons on the journey from region i to region j. Reactions such as slowing down and absorption in the intermediate region will inevitably change the neutron flux in the target area. Considering that the distance that neutrons move will not be too far, this influence will only appear at the junction of two materials with different properties, resulting in a more obvious boundary error between the transient splicing fission matrix and the real fission matrix, which needs to be corrected.

[0082] For example, when there is a boundary reflection layer in the simulated system, there will be an error between this infinite uniform distribution system and the real system. Using the same source distribution, two systems with the same geometric model but different boundaries (one is an infinite uniform model simulated with full reflection boundary conditions, and the other outer layer is a real structure) are calculated with fixed sources, and the fission rate distributions F(uniform) and F(real) of each grid are statistically obtained. F(uniform) and F(real) reflect the corresponding relationship between the two systems to the source, and their ratio is the boundary correction ratio between the infinite uniform model and the real model. Based on the boundary correction ratio, the transient splicing fission matrix is ​​corrected to obtain the corrected transient splicing fission matrix.

[0083] The transient splicing fission matrix calculation method of the above-mentioned core model provided in this embodiment can simulate the transient process of the enrichment, control rods and temperature of the core model under any changing state by splicing the transient splicing fission matrix of the target material properties in the current state based on a pre-established fission matrix database, thereby avoiding the problem that the transient fission matrix method needs to repeatedly calculate the database in the continuous changing process. The calculation method is simple, and by correcting the transient splicing fission matrix based on the distribution boundary information of the target material properties in the current state, the calculated transient splicing fission matrix can be made more in line with the actual situation, thereby improving the calculation accuracy and calculation rate of the transient splicing fission matrix.

[0084] In one embodiment, the fission matrix database provided by this embodiment includes the fission matrix of the core model under the material properties of the control rods fully inserted and fully withdrawn; this embodiment provides a specific implementation method of selecting the corresponding target fission matrix elements from the fission matrix database based on the current state of the target material properties of the core model, and splicing the target fission matrix elements to obtain the transient splicing fission matrix corresponding to the current state of the target material properties:

[0085] During the movement of the control rods of the core model, the intersection position of the inserted control rods and the uninserted control rods is obtained; based on the intersection position, the target fission matrix elements corresponding to the area where the control rods are inserted are obtained from the fission matrix when all the control rods are inserted, and the target fission matrix elements corresponding to the area where the control rods are not inserted are obtained from the fission matrix when all the control rods are removed; the target fission matrix elements corresponding to the area where the control rods are inserted are spliced ​​with the target fission matrix elements corresponding to the area where the control rods are not inserted, so as to obtain the corresponding transient spliced ​​fission matrix during the control rod movement process.

[0086] For transient problems of control rod movement, see Figure 2 The schematic diagram of the splicing of the transient splicing fission matrix during the movement of control rods is shown. Assume that the fission matrix when the control rods are fully inserted is FMA, and the fission matrix when the control rods are fully removed is FMB. The control rods are in a semi-inserted state at a certain moment during the movement of the control rods. When calculating the transient splicing fission matrix at this moment, the boundary line of the junction position where the control rods are inserted and the control rods are not inserted is obtained. The upper half is the control rod inserted state, and the lower half is the control rod not inserted state. Then, the target fission matrix elements corresponding to the area where the control rods are inserted are obtained from the fission matrix FMA when the control rods are fully inserted, and the target fission matrix elements corresponding to the area where the control rods are not inserted are obtained from the fission matrix FMB when the control rods are fully removed. The transient splicing fission matrix Real FM corresponding to the real model during the movement of the control rods is obtained by splicing.

[0087] When splicing the transient fission matrix, the end principle is adopted, that is, g x,y (i, j, t) The selection of FMA or FMB elements depends on the location i where fission is initiated. When the height of i is higher than the control rod height, FMA is selected, otherwise the elements in FMB are selected. By using geometric symmetry, the number of fixed source calculations used in generating FMA and FMB can be reduced. For example, when axial discretization is performed, only one fixed source calculation at the intermediate height position is required to obtain a database of the full height. Since the database is an infinitely uniform model, the geometric properties of the axial direction are the same, and the elements g from j to i are x,y (i,j,t), you can use g with the same height difference x,y (i',j',t) is obtained.

[0088] In one embodiment, the fission matrix database provided by this embodiment includes the fission matrix of the core model under different enrichment values; this embodiment provides a specific implementation method of selecting corresponding target fission matrix elements from the fission matrix database based on the current state of the target material properties of the core model, and splicing the target fission matrix elements to obtain a transient splicing fission matrix corresponding to the current state of the target material properties:

[0089] The boundary lines between different enrichment distribution areas on the fuel rods of the core model are obtained; based on the boundary lines, the target fission matrix elements under the corresponding areas are obtained from the fission matrix database of each enrichment corresponding to the current enrichment of the fuel rods, and the target fission matrix elements under each enrichment distribution area are spliced ​​to obtain the transient spliced ​​fission matrix corresponding to the enrichment change process of the fuel rods.

[0090] Assume that the enrichment of the first region of the fuel rod of the core model is the first enrichment, and the enrichment of the second region is the second enrichment. The fission matrix element in the first region is obtained from the fission matrix of the same enrichment as the first enrichment in the fission matrix database, and recorded as the first target fission matrix element; the fission matrix element in the second region is obtained from the fission matrix of the same enrichment as the second enrichment in the fission matrix database, and recorded as the second target fission matrix element. The first target fission matrix element and the second target fission matrix element are spliced ​​according to the position distribution of the first region and the second region to obtain the transient spliced ​​fission matrix of the current real model during the change of the fuel rod enrichment.

[0091] In one embodiment, the fission matrix database provided by this embodiment includes the fission matrix of the core model at different temperatures; this embodiment provides a specific implementation method of selecting corresponding target fission matrix elements from the fission matrix database based on the current state of the target material properties of the core model, and splicing the target fission matrix elements to obtain a transient spliced ​​fission matrix corresponding to the current state of the target material properties:

[0092] The dividing line between different temperature distribution areas of the core model is obtained; based on the dividing line, the target fission matrix elements under the corresponding area are obtained from the fission matrix database with the same temperature as the current temperature of each area of ​​the core model, and the target fission matrix elements under each temperature distribution area are spliced ​​to obtain the corresponding transient spliced ​​fission matrix during the temperature distribution change in the core model.

[0093] Correspondingly, let the temperature of the first region of the fuel rod of the core model be the first temperature, and the temperature of the second region be the second temperature. The fission matrix element in the first region is obtained from the fission matrix with the same temperature value as the first temperature in the fission matrix database, and recorded as the first target fission matrix element; the fission matrix element in the second region is obtained from the fission matrix with the same temperature value as the second temperature in the fission matrix database, and recorded as the second target fission matrix element. The first target fission matrix element and the second target fission matrix element are spliced ​​according to the position distribution of the first region and the second region to obtain the transient spliced ​​fission matrix of the current real model during the temperature change process.

[0094] In one embodiment, this embodiment provides an implementation method for correcting the transient splicing fission matrix based on the distribution boundary information of the target material properties in the current state to obtain the corrected transient splicing fission matrix, which can be specifically performed with reference to the following steps:

[0095] Step (1): Calculate the boundary correction ratio corresponding to each area based on the distribution boundary information of the target material properties in the current state;

[0096] Using the same source distribution, two systems with the same geometric model but different boundaries (one is an infinite uniform model simulated by total reflection boundary conditions, and the other is a real structure on the outer layer) are calculated with fixed sources, and the fission rate distributions F(uniform) and F(real) of each grid are statistically obtained. F(uniform) and F(real) reflect the corresponding relationship between the two systems to the source, and their ratio is the boundary correction ratio of the infinite uniform model to the real model. The calculation formula for the boundary correction ratio at position i is:

[0097]

[0098] Among them, R i is the boundary correction ratio of position i, F i (real) is the fission rate calculated under the real model, F i (uniform) is the fission rate calculated under the infinite uniform model.

[0099] In a specific embodiment, the above-mentioned regions include a first region and a second region, and the states of the target material properties in the first region and the second region are different; the fission rate corresponding to the real model of the target material properties in the current state is calculated, which is recorded as the first fission rate; the fission rate corresponding to the infinite uniform model under the target material property values ​​in the first region is calculated, which is recorded as the second fission rate; the fission rate corresponding to the infinite uniform model under the target material property values ​​in the second region is calculated, which is recorded as the third fission rate; the ratio of the second fission rate to the first fission rate is calculated to obtain the boundary correction ratio corresponding to the first region; the ratio of the third fission rate to the first fission rate is calculated to obtain the boundary correction ratio corresponding to the second region.

[0100] Taking the calculation of the boundary correction ratio during the movement of the control rod as an example, there is a large error at the junction of the control rods, which needs to be corrected by the control rod correction ratio. The control rod correction ratio is divided into two parts: with control rods and without control rods. In the part above the control rod insertion height z0, the infinite uniform model with full control rod insertion is used to perform a fixed source calculation to obtain F1 (uniform) (i.e., the second fission rate); below the control rod insertion height z0, the infinite uniform model with full control rod insertion is used to perform a fixed source calculation to obtain F2 (uniform) (i.e., the third fission rate). F (real) (i.e., the first fission rate) is calculated using the fixed source of the half-inserted rod model. The complete control rod correction ratio is obtained by the following formula:

[0101]

[0102] The control rod tip effect only affects the area around the control rod junction. The transient splicing fission matrix of any control rod position can be corrected by moving the relative position of the control rod correction ratio in the axial direction, thereby obtaining an accurate transient fission matrix.

[0103] Step (2): Based on the boundary correction ratio corresponding to each region, the matrix elements at the corresponding positions in the transient splicing and fission matrix are corrected to obtain a corrected transient splicing and fission matrix.

[0104] Taking the calculation of the transient splicing fission matrix during the above-mentioned control rod movement as an example, due to the tip effect of the control rod, there is a large error at the junction of the control rods, so it is necessary to correct it through the control rod correction ratio. Fixed source calculations are performed in both infinite uniform model and real model to obtain the fission rate distribution F(uniform) and F(real) of each grid, and the control rod correction ratio can be obtained. Since the control rod tip effect only affects the area around the control rod junction, the transient splicing fission matrix of any control rod position can be corrected by moving the relative position of the control rod correction ratio in the axial direction, thereby obtaining an accurate transient fission matrix.

[0105] In the transient calculation process, the transient splicing fission matrix element G xy (i,j,k) add the corresponding correction ratio R i , generating a new transient splicing fission element G' xy (i, j, k), that is, the calculation formula of the matrix elements of the modified transient splicing fission matrix is:

[0106] G′ xy (i,j,k)=G xy (i,j,k)·R i (7)

[0107] Therefore, in the present embodiment, the calculation of the transient splicing fission matrix during the control rod movement only needs to calculate the transient splicing fission matrix database of the two states of full insertion and full withdrawal of the control rod, as well as F (uniform) and F (real) in the correction ratio, so as to simulate the transient process of arbitrary changes of the control rod. Compared with the transient fission matrix method, the transient splicing fission matrix method reduces the number of fixed source calculations and shortens the calculation time in obtaining the database. It solves the problem of slow database acquisition speed of the transient fission matrix method and the need to repeatedly calculate the database during continuous changes.

[0108] In one embodiment, this embodiment provides steps for establishing a fission matrix database, including:

[0109] The target material properties of all regions in the core model are replaced with a uniform model of the core model with the same material properties, and a fixed source calculation is performed on the uniform model to obtain a fission matrix of the target material properties; fixed source calculation is performed on the uniform model of the core model under each material property to obtain a fission matrix database.

[0110] The fixed source calculation method simulates the uniform model representation, replaces all regional materials in the core with the same material, uses an infinite uniform model to perform fixed source calculations, and statistically obtains the fission matrix under the material properties. The fission matrices of various material properties are prepared into a set of databases. Such calculations only need to be performed once to meet the subsequent calculation models of various geometric arrangements and materials of various properties (within the database range). According to the geometric arrangement of the real model and the material properties of the specific location, the database is spliced ​​to generate a transient spliced ​​fission matrix of the real model. This method can avoid the tedious critical simulation in the transient fission matrix database and save a lot of calculation time.

[0111] Compared with the existing transient fission matrix calculation method, the calculation method of the transient splicing fission matrix provided in this embodiment reduces the number of fixed source calculations in obtaining the database and shortens the calculation time. For the problem of uniform reactor assembly, the radial direction is divided into 17*17 according to the fuel rods, and the axial direction is discretized into n spaces. The existing transient fission matrix requires 17*17*n fixed source calculations, while the transient splicing fission matrix in this embodiment only needs 1 fixed source calculation and 2 fixed source calculations with corrected proportions through geometric symmetry. The problem of slow database acquisition speed of the transient fission matrix method is solved.

[0112] Since the splicing database is used, the transient splicing fission matrix under different actual control rod states can be generated according to the database. By translating the control rod correction ratio, the transient splicing fission matrix can correctly estimate the transient fission matrix under real conditions. In summary, the database and correction ratio only need to be calculated once, which solves the problem of repeated calculation of the database in the continuous change process.

[0113] The transient splicing fission matrix calculation method for the above-mentioned core model provided in this embodiment applies the idea of ​​the splicing fission matrix method to transient calculations, calculates the fission rate distribution database of infinite uniform conditions of materials with different properties, generates a transient splicing fission matrix by splicing to estimate the transient fission matrix, and solves the problem of slow database acquisition speed of the transient fission matrix method; corrects the transient splicing fission matrix by correcting the ratio to make it consistent with the actual situation, and uses the method of moving the control rod to correct the axial position of the ratio to correctly obtain the real transient fission matrix at any control rod position, which solves the problem that the transient fission matrix method needs to repeatedly calculate the database during the continuous change process.

[0114] Based on the above embodiment, this embodiment provides an example of a method for calculating a transient splicing fission matrix using the above core model, see Figure 3 The transient splicing fission matrix calculation flow chart shown in the figure can be specifically performed by referring to the following steps:

[0115] Step 1, calculate the transient splicing fission matrix database of different material properties;

[0116] The transient splicing fission matrix database includes fission matrices corresponding to a uniform model of a core model under various material properties, wherein the various material properties include any one or more of enrichment, control rods and temperature;

[0117] Step 2, calculating the boundary correction ratio;

[0118] Step 3, based on the transient splicing fission matrix database and the current real state of the core model, a transient splicing fission matrix is ​​obtained by splicing, and each matrix element in the transient splicing fission matrix is ​​corrected based on the boundary correction ratio;

[0119] Step 4: Input the modified transient splicing fission matrix as the transient fission matrix into the above formula (4) to solve the transient problem using the neutron kinetic equation.

[0120] Corresponding to the transient splicing fission matrix calculation method of the core model provided in the above embodiment, the embodiment of the present invention provides a transient splicing fission matrix calculation device of the core model, see Figure 4 The schematic diagram of the structure of a transient splicing fission matrix calculation device for a core model is shown, and the device includes the following modules:

[0121] An acquisition module 41 is used to acquire a pre-established fission matrix database; wherein the fission matrix database includes fission matrices corresponding to a uniform model of a core model under various material properties, and the various material properties include any one or more of enrichment, control rods and temperature;

[0122] A splicing module 42 is used to select corresponding target fission matrix elements from the fission matrix database based on the current state of the target material property of the core model, and splice the target fission matrix elements to obtain a transient splicing fission matrix corresponding to the current state of the target material property;

[0123] The correction module 43 is used to correct the transient splicing and fission matrix based on the distribution boundary information of the target material properties in the current state to obtain a corrected transient splicing and fission matrix.

[0124] The transient splicing fission matrix calculation device of the above-mentioned core model provided in this embodiment can simulate the transient process of the enrichment, control rods and temperature of the core model under arbitrary changing states by splicing the transient splicing fission matrix of the target material properties in the current state based on a pre-established fission matrix database, thereby avoiding the problem that the transient fission matrix method needs to repeatedly calculate the database in the continuous changing process. The calculation method is simple, and by correcting the transient splicing fission matrix based on the distribution boundary information of the target material properties in the current state, the calculated transient splicing fission matrix can be made more in line with the actual situation, thereby improving the calculation accuracy and calculation rate of the transient splicing fission matrix.

[0125] The implementation principle and technical effects of the device provided in this embodiment are the same as those of the aforementioned embodiments. For the sake of brief description, for matters not mentioned in the device embodiment, reference may be made to the corresponding contents in the aforementioned method embodiment.

[0126] An embodiment of the present invention provides an electronic device, which includes a processor and a memory. The memory stores a computer program that can be run on the processor. When the processor executes the computer program, the steps of the method provided in the above embodiment are implemented.

[0127] An embodiment of the present invention provides a computer-readable medium, wherein the computer-readable medium stores computer-executable instructions. When the computer-executable instructions are called and executed by a processor, the computer-executable instructions prompt the processor to implement the method described in the above embodiment.

[0128] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system described above can refer to the corresponding process in the aforementioned embodiment, and will not be repeated here.

[0129] The computer program product of the transient splicing fission matrix calculation method and device for the core model provided in the embodiments of the present invention includes a computer-readable storage medium storing program code. The instructions included in the program code can be used to execute the methods described in the previous method embodiments. The specific implementation can be found in the method embodiments, which will not be repeated here.

[0130] In addition, in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0131] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0132] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0133] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for calculating the transient splicing fission matrix of a core model, characterized in that: include: Acquire a pre-established fission matrix database; wherein the fission matrix database includes fission matrices corresponding to a uniform model of a core model under multiple material properties, wherein the multiple material properties include any one or more of enrichment, control rods, and temperature; Based on the current state of the target material property of the core model, corresponding target fission matrix elements are selected from the fission matrix database, and based on the target fission matrix elements, a transient spliced ​​fission matrix corresponding to the current state of the target material property is obtained by splicing; Based on the distribution boundary information of the target material property in the current state, the transient splicing fission matrix is ​​corrected to obtain a corrected transient splicing fission matrix; The step of correcting the transient splicing fission matrix based on the distribution boundary information of the target material property in the current state to obtain a corrected transient splicing fission matrix includes: Each region includes a first region and a second region, and the target material property has different states in the first region and the second region; the fission rate corresponding to the real model of the target material property in the current state is calculated, recorded as the first fission rate; the fission rate corresponding to the infinite uniform model under the target material property value of the first region is calculated, recorded as the second fission rate; the fission rate corresponding to the infinite uniform model under the target material property value of the second region is calculated, recorded as the third fission rate; the ratio of the second fission rate to the first fission rate is calculated to obtain the boundary correction ratio corresponding to the first region; the ratio of the third fission rate to the first fission rate is calculated to obtain the boundary correction ratio corresponding to the second region; Based on the boundary correction ratio corresponding to each region, the matrix elements at corresponding positions in the transient splicing and fission matrix are corrected to obtain a corrected transient splicing and fission matrix.

2. The method according to claim 1, characterized in that The fission matrix database includes the fission matrix of the core model under the material properties of the control rods fully inserted and the control rods fully removed; The step of selecting corresponding target fission matrix elements from the fission matrix database based on the current state of the target material property of the core model, and obtaining a transient spliced ​​fission matrix corresponding to the current state of the target material property based on the splicing of the target fission matrix elements comprises: During the movement of the control rods of the core model, obtaining the boundary position between where the control rods are inserted and where the control rods are not inserted; Based on the intersection position, a target fission matrix element corresponding to the area where the control rods are inserted is obtained from the fission matrix when the control rods are fully inserted, and a target fission matrix element corresponding to the area where the control rods are not inserted is obtained from the fission matrix when the control rods are fully removed; The target fission matrix elements corresponding to the area where the control rod is inserted are spliced ​​with the target fission matrix elements corresponding to the area where the control rod is not inserted, so as to obtain the transient spliced ​​fission matrix corresponding to the movement of the control rod.

3. The method according to claim 1, characterized in that The fission matrix database includes the fission matrix of the core model at different values ​​of the enrichment; The step of selecting corresponding target fission matrix elements from the fission matrix database based on the current state of the target material property of the core model, and obtaining a transient spliced ​​fission matrix corresponding to the current state of the target material property based on the splicing of the target fission matrix elements comprises: Obtaining the boundary lines between different enrichment distribution areas on the fuel rods of the core model; Based on the dividing line, the target fission matrix elements in the corresponding area are obtained from the fission matrix database of each enrichment level that is equal to the current enrichment levels of the fuel rod, and the target fission matrix elements in each enrichment distribution area are spliced ​​to obtain the transient spliced ​​fission matrix corresponding to the enrichment change process of the fuel rod.

4. The method according to claim 1, characterized in that: The fission matrix database includes the fission matrix of the core model at different temperatures; The step of selecting corresponding target fission matrix elements from the fission matrix database based on the current state of the target material property of the core model, and obtaining a transient spliced ​​fission matrix corresponding to the current state of the target material property based on the splicing of the target fission matrix elements comprises: Obtaining a boundary line between different temperature distribution areas of the core model; Based on the dividing line, the target fission matrix elements in the corresponding area are obtained from the fission matrix database of each temperature corresponding to the current temperature of each area of ​​the core model, and the target fission matrix elements in each temperature distribution area are spliced ​​to obtain the transient spliced ​​fission matrix corresponding to the temperature distribution change process in the core model.

5. The method according to claim 1, characterized in that The steps of establishing the fission matrix database include: Replacing the target material properties of all regions in the core model with the same material properties to simulate a uniform model of the core model, performing fixed source calculation on the uniform model, and obtaining a fission matrix of the target material properties; Fixed source calculation is performed on the uniform model of the core model under various material properties to obtain the fission matrix database.

6. A transient splicing fission matrix calculation device for a core model, characterized in that: include: An acquisition module, used for acquiring a pre-established fission matrix database; wherein the fission matrix database includes fission matrices corresponding to a uniform model of a core model under multiple material properties, wherein the multiple material properties include any one or more of enrichment, control rods and temperature; A splicing module, used for selecting corresponding target fission matrix elements from the fission matrix database based on the current state of the target material property of the core model, and splicing the target fission matrix elements to obtain a transient splicing fission matrix corresponding to the current state of the target material property; A correction module, used for correcting the transient splicing fission matrix based on the distribution boundary information of the target material property in the current state to obtain a corrected transient splicing fission matrix; Each region includes a first region and a second region, and the states of the target material properties in the first region and the second region are different; the correction module is used to calculate the fission rate corresponding to the real model of the target material properties in the current state, recorded as the first fission rate; calculate the fission rate corresponding to the infinite uniform model under the target material property values ​​of the first region, recorded as the second fission rate; calculate the fission rate corresponding to the infinite uniform model under the target material property values ​​of the second region, recorded as the third fission rate; calculate the ratio of the second fission rate to the first fission rate to obtain the boundary correction ratio corresponding to the first region; calculate the ratio of the third fission rate to the first fission rate to obtain the boundary correction ratio corresponding to the second region; based on the boundary correction ratios corresponding to the regions, the matrix elements at the corresponding positions in the transient splicing fission matrix are corrected to obtain a corrected transient splicing fission matrix.

7. An electronic device, characterized in that: include: processor and storage device; The storage device stores a computer program, which, when executed by the processor, performs the method according to any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are executed.

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